Paul Mansky

Bio: Paul Mansky is an academic researcher from University of Massachusetts Amherst. The author has contributed to research in topics: Polymer & Layer (electronics). The author has an hindex of 14, co-authored 41 publications receiving 3650 citations. Previous affiliations of Paul Mansky include Symyx Technologies & Unilever.

Controlling Polymer-Surface Interactions with Random Copolymer Brushes

Abstract: A simple technique for precisely controlling the interfacial energies and wetting behavior of polymers in contact with solid surfaces is described. End-functionalized statistical random copolymers of styrene and methylmethacrylate were synthesized, with the styrene fraction f varying from 0 to 1, and were end-grafted onto silicon substrates to create random copolymer brushes about 5 nanometers thick. For f < 0.7, polystyrene (PS) films (20 nanometers thick) rapidly dewet from the brushes when heated well above the glass transition temperature. The contact angle of the resulting polymer droplets increased monotonically with decreasing f . Similar behavior was observed for poly(methylmethacrylate) (PMMA) films but with an opposite dependence on f . The interfacial energies of the random copolymer brushes with PS and PMMA were equal when f was about 0.6. Thus, precise control of the relative surface affinities of PS and PMMA was possible, demonstrating a way to manipulate polymer-surface interactions.

Controlled Synthesis of Polymer Brushes by “Living” Free Radical Polymerization Techniques

Abstract: The preparation of a wide variety of unique polymer brush structures can be accomplished by “living” free radical polymerization of vinyl monomers from surface-tethered alkoxyamines or from tethered α-halo esters in the presence of (PPh3)2NiBr2. The use of a “living” free radical process permits the molecular weight and polydispersity of the covalently attached polymer chains to be accurately controlled while also allowing the formation of block copolymers by the sequential growth of monomers from the surface. These block and random copolymer brushes have been used to control surface properties.

Polymers on nanoperiodic, heterogeneous surfaces

Abstract: Herein we establish a relationship between controlled nanoscale surface interactions and subsequent macromolecular ordering. Striped surfaces of oxide and metal are generated over large areas, where the stripe width is comparable to the size of a polymer molecule. Homopolymers are found to anisotropically dewet such surfaces, while incompatible polymer mixtures phase separate at the substrate/polymer interface on a molecular level. An orientation of lamellar block copolymer microdomains normal to the surface is found, when substrate and polymer length scales are commensurate.

Ordered diblock copolymer films on random copolymer brushes

Abstract: Optical microscopy, neutron reflectivity, and small angle neutron scattering studies were used to investigate the structure of thin films of symmetric diblock copolymers of P(dS-b-MMA) as the interactions between the copolymer and the substrate were changed in a systematic manner. In cases where there was a strong preferential segregation of one of the components to the substrate, the lamellar microdomains were oriented parallel to the film surface. However, on a nearly neutral substrate, a mixed morphology was found where the lamellae adjacent to the free surface are oriented parallel to the plane of the film, while the lamellae adjacent to the substrate are oriented normal to the plane of the film.

Interfacial Segregation in Disordered Block Copolymers: Effect of Tunable Surface Potentials

Abstract: The response of disordered P({ital d}-S-{ital b}-MMA) diblock copolymers to variable strength surface fields has been studied by neutron reflectivity. Surface interactions were controlled by end grafting P(S-{ital r}-MMA) random copolymers with various styrene contents onto Si substrates. The degree interfacial segregation of the block copolymer was proportional to the surface potential. A first-order transition in the degree of segregation was observed as the brush composition was varied. Conditions were found which yielded neutral boundary conditions {ital simultaneously} at the vacuum and substrate interfaces. {copyright} {ital 1997} {ital The American Physical Society}

Nanoparticle Polymer Composites: Where Two Small Worlds Meet

Abstract: The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous electrical, optical, or mechanical properties. Recent advances reveal routes to exploit both enthalpic and entropic interactions so as to direct the spatial distribution of nanoparticles and thereby control the macroscopic performance of the material. For example, by tailoring the particle coating and size, researchers have created self-healing materials for improved sustainability and self-corralling rods for photovoltaic applications. A challenge for future studies is to create hierarchically structured composites in which each sublayer contributes a distinct function to yield a mechanically integrated, multifunctional material.